1. Field of the Invention
This invention relates to the manufacture of sodium sulphur cells and is concerned more particularly with the filling of the sodium reservoir of such a cell with liquid sodium.
2. Prior Art
Sodium sulphur cells for experimental purposes have been made in small quantities and it is readily possible to fill the sodium reservoir by carrying out the filling operation in a closed chamber filled with a suitable inert gas, the cell being sealed, before removal from the chamber. Such a technique, whilst convenient for making a few cells at a time, does not lend itself to continuous quantity production of cells. The chamber has to be opened after sealing of the cell and then has to be purged of any air before the next batch of cells can be filled.
For this reason, a number of proposals have been made (see for example U.S. Pat. Nos. 4,102,042; 4,167,807; 4,189,530 and 4,204,035) for solidifying the sodium before it is loaded into a sodium reservoir for the cell. The use of solid sodium however puts constraints on the shaping of the cell if the sodium has to be put directly into the cell or requires the provision of a separate sodium reservoir. In either case, complete filling of all the available anode space is not generally possible.